This volume on aliphatic carcinogens brings the structure-activity relationship aspect of the series to completion. The large Section 5.2.1.3 on Nitroso Compounds, the writing of which began during the previous grant year, will be completed. Since the mass of literature material which accumulated in the past few years has been sorted and filed, the writing of the different sections, as proposed in the original application, will now proceed as scheduled but at an increasing pace. These sections entail all the other types of alkylting agents besides the nitrosamines; halogenated aliphatic hydrocarbons; PCB's and halogenated hydrocarbon pesticides; polar-nonpolar detergent-like compounds; naturally occurring carcinogens of plant, fungal and microbial origin; asbestos and metal carcinogens; and certain special areas of chemical carcinogenesis.